Double concave question

03-18-2012, 05:25 PM

For Mr Neville or anybody who can drop a cent here.
Threads have been posted about adding a 5th fin of a potato hence flattening the spine towards the back fins. What would be the actual outcome of flattening the spine from the end of the front fins to the end of the board?

As I understand it concaves work like this; a single will channel water down the board into a narrowing funnel thus creating a faster water flow using the Venturi effect. A single to double and a full double do the same thing but also create a faster flow of water over the ridge between the double concaves as well when you are turning helping accelerate out of turns. By flattening it a little it might reduce this effect somewhat but then you still have the double concaves and if they are deep enough it would be minimal I would have thought. Though as already suggested without that defined ridge it might be harder to get it over on the rail if you didn't have a fin in there but then again in little waves maybe it isn't that critical.

yeah one other note is that concaves, both single and double can actually increase the rail rocker when compared to the centerline rocker. Essentially, if you have a dramatic bottom contour, more than likely, you will also get a a bit more rail rocker. when applied to hybrids, this is a great way to elevate performance while keeping the board user friendly.